Absorbent tissue products such as paper towels, facial tissues, bath tissues, napkins, and other similar products are designed to include several important properties. For example, the products should have good bulk, a soft feel and should be highly absorbent. Unfortunately, in some instances, it is difficult to produce a tissue product that is soft and also absorbent.
For instance, silicone compositions are sometimes added to a tissue product to improve softness. However, in some cases, the application of the silicone composition can result in a tissue product with reduced absorbency. For example, a tissue product applied with a silicone composition is often stored in warehouses between the time it is manufactured and the time it is shipped to distributors. During such time period, the tissue product may be subjected to various non-ideal conditions, e.g., elevated temperatures and humidity levels, extended periods of time, etc. While subjected to such conditions, it has been found that the absorbent capabilities of the tissue product decreases.
Consequently, a need currently exists for an improved tissue product that is soft and absorbent. A need also exists for a tissue product containing an improved softening composition that promotes hydrophobic stability.
The present invention is directed to a tissue product including a paper web containing cellulosic fibers and a softening treatment applied to at least one surface of the paper web. The softening treatment includes a softening compound and a polymerization inhibitor.
In one embodiment, for example, the softening compound can contain an amino-modified polysiloxane that bonds to the fibers in the paper web. Further, in some embodiments, the softening compound may include a non-amino modified polysiloxane. In some embodiments, the non-amino modified polysiloxane may be combined with the amino-modified polysiloxane to form an emulsion. In other embodiments, the polysiloxanes can be separately applied to the tissue product, such as in separate emulsions or solutions.
As stated above, the softening treatment also includes a polymerization inhibitor that is capable of inhibiting the polymerization of the softening compound when the compound is subjected to non-ideal conditions. In general, any compound or molecule that can inhibit the polymerization of another compound or molecule under certain conditions can be utilized as a polymerization inhibitor in the present invention. For example, in some embodiments, the polymerization inhibitor can contain a siloxane compound having the following formula: 
wherein z is an integer greater than 0. Typically, z is less than or equal to 10, and particularly less than or equal to 6. In one embodiment, for example, z is equal to 1 so that the resulting polymerization inhibitor is a disiloxane. The R1-R6 moieties can be C1 or greater alkyl stubstituents.
In one particular embodiment, an alkyl disiloxane may be utilized, such as hexamethyl disiloxane having the following formula: 
Although not required, the molecular weight of the polymerization inhibitor can be less than the molecular weight of the polysiloxane softening compound. For example, in some embodiments, the molecular weight of the polymerization inhibitor can be from about 100 to about 1000, and particularly between about 145 to about 450.
The polymerization inhibitor may be combined with the softening compound before or after the softening compound is applied to the tissue product. For example, in one embodiment, a polymerization inhibitor is combined with an amino-functional polysiloxane compound to form a softening treatment that is then emulsified in water using an appropriate surfactant. In another embodiment, the polymerization inhibitor is combined with an already emulsified amino-functional polysiloxane compound to form the softening treatment.
In general, the polymerization inhibitor may be present in the mixture or emulsion in any amount. For example, in one embodiment, the polymerization inhibitor is present in an amount from about 1% to about 50% by weight of the total weight of the softening treatment, and particularly from about 1% to about 20%. In one particular embodiment, for instance, an emulsion is formed containing about 35% by weight of polysiloxane solids, about 2% by weight hexamethyl disiloxane, with the balance of the treatment weight being water, a surfactant, and/or other emulsifying materials.
Other features and aspects of the present invention are discussed in greater detail below.